Showing papers on "Nuclear DNA published in 1978"
TL;DR: Results suggest that micrococcal nuclease selectively excises nucleosomes from oviduct chromatin containing the ovalbumin gene, which permits the recovery of mononucleosomes in the 1SF which are enriched in the oval bumin gene and oligonucleotides in the 2SFWhich are depleted in this sequence.
264 citations
TL;DR: In dry seeds, fragmentation of nuclear DNA and activation of DNases occur in vivo during embryo senescence, which could be the source of chromosomal aberrations and impaired transcription observed when seeds of low viability germinate.
Abstract: In dry seeds, fragmentation of nuclear DNA and activation of DNases occur in vivo during embryo senescence. This loss of DNA integrity could be the source of chromosomal aberrations and impaired transcription observed when seeds of low viability germinate.
160 citations
TL;DR: The pattern of methylation was different for each of the three organisms studied: Saccharomyces cerevisiae contained only 5-methylcytosine; Tetrahymena pyriformis contained only N6-methyladenine; and Chlamydomonas reinhardi contained both modified bases.
Abstract: We have analyzed the nature/content of methylated bases in the nuclear DNA of three unicellular eucaryotes. The pattern of methylation was different for each of the three organisms studied: Saccharomyces cerevisiae contained only 5-methylcytosine; Tetrahymena pyriformis contained only N6-methyladenine; and Chlamydomonas reinhardi contained both modified bases.
155 citations
TL;DR: Profiles of DNA distribution in histologically benign tumors revealed a large diploid population with a few nuclei in DNA synthesis, as well as a small premitotic population that contains a 4C DNA complement.
Abstract: Flow cytometry (FCM) is a technique that measures the quantity of DNA contained in individual nuclei and records a frequency distribution of the DNA content per nucleus in the sampled cell population. Nuclei from a variety of human brain-tumor types were isolated by means of tissue grinding, purified by centrifugation through 40% sucrose (15 minutes at 4000 rpm), fixed with 10% formalin, stained with acriflavin-Feulgen, and analyzed by FCM. Profiles of DNA distribution in histologically benign tumors, such as meningiomas, pituitary adenomas, neuroblastomas, and low-grade astrocytomas, revealed a large diploid population (2C) with a few nuclei in DNA synthesis, as well as a small premitotic population (G2 cells) that contains a 4C DNA complement. In contrast, malignant gliomas, including glioblastomas, consist of more cells in DNA synthesis; these tumor cells show a highly variable distribution of ploidy consisting not only of diploid, and/or aneuploid, but also of triploid, tetraploid, and possibly octaploid populations. Also, a large variability between different regions of each tumor was always observed. In contrast, metastatic brain tumors, despite the fact that they contain a considerable number of cells undergoing DNA synthesis, demonstrate little variability within each individual tumor. The ability to rapidly characterize the cell populations of human brain tumors with FCM may enhance the effectiveness of their clinical management.
104 citations
TL;DR: Kinetic and chemical analysis show that the haploid genome of Leishmania donovani has between 4.6 and 6.5 X 10(7) Kb pairs of DNA, and that the two major rRNA species have sedimentation values of 26S and 16S, respectively.
Abstract: Kinetic and chemical analysis show that the haploid genome of Leishmania donovani has between 4.6 and 6.5 X 10(7) Kb pairs of DNA. Cot analysis shows that the genome contains 12% rapidly reassociating DNA, U3% middle repetitive DNA with an average reiteration frequency of 77 and 62% single copy DNA. Saturation hybridization experiments show that 0.82% of the nuclear DNA is occupied by rRNA coding sequences. The average repetition frequency of these sequences is determined to be 166. Sedimentation velocity studies indicate the two major rRNA species have sedimentation values of 26S and 16S, respectively. The arrangement of the rRNA genes and their spacer sequences on long strands of purified rDNA has been determined by the examination of the structure of rRNA:DNA hybrids prepared for electron microscopy by the gene 32-ethidium bromide technique. Long DNA strands are observed to contain several gene sets (16S + 26S). One repeat unit contains the following sequences in the order given: (a) A 16S gene of length 2.12 Kb, (b) An internal transcribed spacer (Spl) of length 1.23 Kb, which contains a short sequence that may code for a 5.8S rRNA, (C) 26S gene with a length of 4.31 Kb which contains an internal gap region of length 0.581 Ib, (d) An external spacer of average length 5.85 Kb.
97 citations
TL;DR: Analysis of viral DNA and RNA synthesis in infected cells by electron microscopic autoradiography and biochemical techniques supports the conclusion that FV 3 DNA synthesis is initiated in the nucleus and completed in the cytoplasm.
86 citations
TL;DR: The nuclear volume (Nv), cell volume (Cv) and cell surface area (Cs) of erythrocytes from 26 anuran species show a linear and direct correlation with the nuclear DNA content; the Cs/Cv ratio tends to decrease as DNA increases.
Abstract: The nuclear volume (Nv), cell volume (Cv) and cell surface area (Cs) of erythrocytes from 26 anuran species show a linear and direct correlation with the nuclear DNA content; the Cs/Cv ratio tends to decrease as DNA increases. Analogous phenomena are found in urodeles possessing less than 70 pg/N of DNA, whereas in those with a larger genome there is a trend towards stabilization of the Cs/Cv ratio. The same mechanisms appear to control the ratios of genome sizes to cell sizes within the amphibians and possibly in other vertebrates as well. The former, however, seem to avail themselves to a greater extent of the adaptive properties inherent in their genome and cell size variations.
62 citations
TL;DR: Evidence is presented that the first nuclear division does not occur until the pseudo-mycelium grows to a minimum length equal to or greater than the diameter of the mother cell and until the cells pass through a minimum time period which probably reflects the time necessary to complete nuclear DNA replication.
49 citations
TL;DR: In gradients the pattern of DNA synthesis in the cell cycle mutants cdc2 and 6, thought to make incomplete or faulty DNA at the restrictive temperature (Hartwell, 1974), closely resembled that of the wild-type.
Abstract: Using alkaline sucrose gradients the mechanism of DNA synthesis has been investigated in both log-phase and synchronised cultures of the yeast Saccharomyces cerevisiae. DNA synthesis proceeds via a heterogeneous population of single-stranded intermediates between 7 and 60x106 daltons in size. The size of these molecules and a comparison of their behaviour in log-phase and synchronised cultures suggests they are nascent or completed replicons. The progressive increase in molecular weight of these intermediates during S in synchronous cultures was used as a measure of the rate of DNA synthesis per single strand. During the first half of the period of DNA synthesis in the culture, the observed rate of elongation was 0.82x106 daltons/min. Later in S, an apparent increase in rate was detected, but this may have reflected the joining of completed replicons. In our gradients the pattern of DNA synthesis in the cell cycle mutants cdc2 and 6, thought to make incomplete or faulty DNA at the restrictive temperature (Hartwell, 1974), closely resembled that of the wild-type.
49 citations
TL;DR: The nuclear DNA amount varies threefold among species of acridid grass hoppers, and Males from the northern race of Cryptobothrus chrysophorus contain about 20% more nuclear DNA than males from the southern race.
Abstract: The nuclear DNA amount varies threefold among species of acridid grasshoppers. DNA amount is correlated with the total chromosome volume, as measured at metaphase of mitosis. Despite the large-scale variation in DNA amount and in the total volume of chromosome material there is a striking uniformity in respect of the relative sizes of chromosomes within complements. Males from the northern race of Cryptobothrus chrysophorus contain about 20% more nuclear DNA than males from the southern race. The DNA difference may be explained by super-numerary segments within chromosomes in the northern populations. The magnitude of the DNA variation between these races is indicative of substantial genetic divergence. It may well be that the two races merit separate specific ranking.
46 citations
TL;DR: A comparison between DNA contents and the proportion of repeated DNA sequences indicated that, in Allium, increase in the genome size is not exclusively due to variations in the proportions of repetitive DNA.
Abstract: The genomes of seven plant species belonging to the genus Allium and exhibiting a threefold variation in their nuclear DNA content were analyzed by studying their reassociation kinetics, equilibrium centrifugation behavior in neutral CsCl gradients, and melting properties. The reassociation kinetics experiments revealed the presence of 44-65% repeated DNA sequences. A comparison between DNA contents and the proportion of repeated DNA sequences indicated that, in Allium, increase in the genome size is not exclusively due to variations in the proportions of repetitive DNA. The total DNA as well as the various repetitive DNA fractions in all the Allium species examined exhibited, in spite of a few differences, a gross similarity in their behavior in neutral CsCl gradients and in their melting properties.
TL;DR: Data suggest that the absolute amount of chloroplast and nuclear DNA found within a cell remains constant but that the amount ofchloroplast DNA per plastid is inversely proportional to the number of chloroplasts to which that DNA must be distributed.
Abstract: Changes in the physiological state of the multiplastidic alga Olisthodiscus luteus result in a shift in chloroplast complement from 33 to 21 plastids. The effect of this induced change in organelle complement on nuclear and chloroplast DNA levels has been analyzed. Data suggest that the absolute amount of chloroplast and nuclear DNA found within a cell remains constant but that the amount of chloroplast DNA per plastid is inversely proportional to the number of chloroplasts to which that DNA must be distributed.
TL;DR: In this paper, the subunit composition of Physarum chromatin containing DNA complementary to 19 S and 26 S ribosomal RNA was studied by hybridization of 32P-labeled RNA to the DNA of chromatin subunits generated by staphyloeoccal nuclease digestion and separated on sucrose gradients.
TL;DR: The diversity, abundance, and DNA sequence representation of poly(adenylic acid) containing RNA derived from cells of Achlya ambisexualis cultured in defined and undefined media have been determined and indicate that approximately 10% of the RNA is transcribed from reiterated DNA sequences while the remainder is transcribes from single copy sequences.
Abstract: The diversity, abundance, and DNA sequence representation of poly(adenylic acid) containing RNA derived from cells of Achlya ambisexualis cultured in defined and undefined media have been determined The kinetics of hybridization of polyadenylated RNA with complementary DNA were the same for both culture conditions and revealed the presence of three frequency classes containing 29, 220, and 3000 different sequences of an average length of 1150 nucleotides Complexity estimates derived from experiments in which polyadenylated RNA was hybridized to unique sequence DNA were in good agreement with these results The kinetics of hybridization of complementary DNA with an excess of nuclear DNA indicate that approximately 10% of the RNA is transcribed from reiterated DNA sequences while the remainder is transcribed from single copy sequences
TL;DR: Evidence has been obtained concerning the structure of Dictyostelium rDNA which agrees with the finding that the rDNA molecules are not covalently attached to the chromosomes of this organism.
Abstract: Antibodies, shown to be specific for DNA/RNA hybrids, have been covalently attached to CNBr-activated Sepharose. The resultant affinity resin specifically binds DNA/RNA hybrids and has been used to enrich for the DNA which codes for rRNA in the slime mold Dictyostelium discoideum. By utilizing the technique of R-loop formation, DNA molecules containing the rRNA genes were isolated from total nuclear DNA in a double-stranded form. These rDNA molecules, which were recovered by high salt elution from the affinity resin, were typically 15-40 kbp in length, and thus contained DNA sequences adjacent to the selected sequences coding for the 17S and 26S rRNAs. In addition, evidence has been obtained concerning the structure of Dictyostelium rDNA which agrees with the finding (Taylor et al. (1977) ICN-UCLA Symp. Mol. Cell. Biol. 8, 309-313) that the rDNA molecules are not covalently attached to the chromosomes of this organism.
TL;DR: The number of structural genes coding for a sample of electrophoretically detectable enzymes was determined for seven diploid species of Crepis, suggesting that gene number is conserved.
Abstract: Stability of structural gene number in diploid species with different amounts of nuclear DNA and different chromosome numbers
TL;DR: The whole W chromosome, or at least most of it, is heterochromatic and transcriptionally inactive in somatic tissues, however, there are indications that this inactivation is specific for somatic tissue while in the previtellogenetic oocyte of the adult ovary the W chromosome is transcriptionally active.
TL;DR: The [14C]-labeled monoazido analog of ethidium, 3-amino-8-azido-5-ethyl-6-phenylphenanthridinium chloride, when mixed with yeast cells and photolyzed, produced covalent adducts with both nuclear and mitochondrial DNA via the light-generated nitrene.
Abstract: The [14C]-labeled monoazido analog of ethidium, 3-amino-8-azido-5-ethyl-6-phenylphenanthridinium chloride, when mixed with yeast cells and photolyzed, produced covalent adducts with both nuclear and mitochondrial DNA via the light-generated nitrene. The binding efficiency was about 12 times higher in mitochondrial than nuclear DNA. Moreover, the parent ethidium bromide at a 5-fold excess was an effective competitor for the binding of the monoazide analog with mitochondrial DNA, but not with nuclear DNA.
TL;DR: Findings provide some of the groundwork for future attempts to completely purify and characterize those activities in the soluble component of cell lysates which are involved in DNA replication.
Journal Article•
TL;DR: The results indicate that immature squamous metaplasia and mild dysplasia are frequently transient in DES-exposed females, unlike the more rarely observed moderate and severe dysplasias, which appear to be persistent based on the study of a few cases.
TL;DR: Two nuclear DNA fractions from Drosophila hydei were isolated by silver ion and actinomycin D binding and centrifugation in isopycnic salt gradients and neither fraction is composed of nor does it contain any highly repetitive simple sequence DNA, as shown by melting and reassociation studies.
Abstract: Two nuclear DNA fractions from Drosophila hydei were isolated by silver ion and actinomycin D binding and centrifugation in isopycnic salt gradients. Neither fraction is composed of nor does it contain any highly repetitive simple sequence DNA, as shown by melting and reassociation studies. — One fraction has a CsCl density of 1.702 g/cm3 and hybridizes in situ with the β-heterochromatin of the chromocenter in polytene cells. This DNA fraction was found to be replicated during polytenization. In diploid cells this 1.702 g/cm3 component hybridizes to the heterochromatin of all four large autosome pairs, the middle part of the long arm of the Y-chromosome, but not to the X-heterochromatin. — A second fraction has a CsCl density of 1.697 g/cm3 and hybridizes in situ with polytene cells to the chromocenter and the nucleolus, but on metaphase chromosomes only to the nucleolus organizer regions.
TL;DR: This article investigated the possibility of sequence of homology between yeast DNA and one of the double-stranded RNAs present in many strains of Saccharomyces cerevisiae and found no such homology.
Abstract: We investigated the possibility of sequence of homology between yeast DNA and one of the double-stranded RNAs present in many strains of Saccharomyces cerevisiae These double-stranded RNAs are encapsidated in virus-like particles, which appear to be similar to the viruses of higher fungi Contrary to a recent report (M Vodkin, J Virol 21:516--521, 1976), we find no such homology
TL;DR: The trend in evolution of this genus seems towards increase in DNA content since the cultivated Oryza species, presumable being more advanced than the wild species, contained more DNA per nucleus than theWild species.
TL;DR: Two major highly repetitive satellites have been isolated from nuclear DNA of Drosophila hydei by sequential centrifugations in Ag+/Cs2SO4, actinomycin D/CsCl and CsCl, and it was concluded that the 1.696 satellite is the only major DNA component of the X-heterochromatin besides minor DNA fractions.
Abstract: Two major highly repetitive satellites have been isolated from nuclear DNA of Drosophila hydei by sequential centrifugations in Ag+/Cs2SO4, actinomycin D/CsCl and CsCl. Their CsCl-densities are 1.696 and 1.714 g/cm3. In diploid larval brains they comprise about 13% and 4% respectively of the DNA. Both satellites are localized and chromosome specific. The 1.696 component was shown to be derived from the X-heterochromatin by comparison of different stocks containing different amounts of X-heterochromatin and by in situ hybridization of the 125I-labelled light single strand of this satellite. Since the amount of X-heterochromatin equals the amount of this satellite it was concluded that the 1.696 satellite is the only major DNA component of the X-heterochromatin besides minor DNA fractions (e.g. rDNA). The other highly repetitive satellite (1.714 g/cm3) hybridized in situ to all four acrocentric autosome pairs of D. hydei, but neither to the X nor to the small dot-like sixth chromosome, and not to the Y.
TL;DR: Chloroplast DNA constituted between 4.3% and 0.25% of the total leaf DNA in these species, and was present as 5 to 20 copies in each chloroplast.
Abstract: Triton X-100 solubilized chloroplast DNA but not nuclear DNA from a mixture of chloroplasts and nuclei. The buoyant density of chloroplast DNA was different from that of the satellite DNA in all of the species examined (Phaseolus coccineus, Cucumis sativus, Cucumis melo, Antirrhinum majus, Vicia faba, Oenothera fruiticosa youngii). Chloroplast DNA constituted between 4.3% and 0.25% of the total leaf DNA in these species, and was present as 5 to 20 copies in each chloroplast.
TL;DR: The nuclear DNA content of amoebae and protoplasmodia of five sublines of Echinostelium minutum, isolate D-3, has been determined by Feulgen-cytophotometry, and data suggest that the plasmodic develop apogamically, with no alternation of distinct haploid and diploid life cycle stages.
TL;DR: Single-stranded DNA isolated from cultured embryonic chicken cells and analyzed showed interspersion of coding and non coding DNA sequences and susceptibility of active genes to certain nucleasic attacks.
Abstract: Single-stranded DNA (ssDNA) isolated from (and amounting to 1.5-2% of) native nuclear DNA of cultured embryonic chicken cells labelled 1-2 days with 3H-thymidine was analyzed by self-hybridization, hydroxyapatite chromatography (HAC) partial digestion with S1 nuclease, isopycnic centrifugation. Two main fractions were rehybridized to excess amounts of bulk nuclear DNA or total cytoplasmic RNAs. The major fraction, equivalent to 75% of total ssDNA, consists of unique DNA sequences, apparently derived from multiple coding regions of the cell genome, since they are not self-reassociating but are hybridizable to the non repetitious portion of bulk nuclear DNA and 40-45% of them are complementary to cell RNAs. About half of these ssDNA sequences hybridizable to cell RNAs seem to be closely connected with molecules belonging to the minor ssDNA fraction. The latter fraction consists of self-reassociating, moderately repeated DNA sequences, mainly derived from non coding regions of the cell genome. These findings are discussed in the light of others, showing interspersion of coding and non coding DNA sequences and susceptibility of active genes to certain nucleasic attacks.
TL;DR: It is suggested that saltatory replication of certain DNA sequenes, diversification of reiterated DNA sequences, and loss of DNA play an important role in the evolution of orchids.
Abstract: The species- and genus-specific DNA content, average base composition of nuclear DNA, presence or absence of satellite DNA, the percentage of heterochromatin and other characteristics of nuclear DNA and nuclear structure allow to deduce the molecular changes which accompanied, or more probably caused, cladogenesis in the orchids studied. It is suggested that saltatory replication (generative amplification) of certain DNA sequenes, diversification of reiterated DNA sequences, and loss of DNA play an important role in the evolution of orchids.—The relationship between changes of genome composition and of nuclear structure and ultrastructure is discussed on the basis of cot curves, heterochromatin staining with Giemsa (C banding), electron microscopy of nuclei, and molecular hybridization in situ.
TL;DR: Three DNA polymerase activities, A, B and C, were identified in extracts of exponentially growing synchronous cultures of Chlamydomonas reinhardii, and DNA polymerases A and B were characterized in detail.
Abstract: Three DNA polymerase activities, A, B and C, were identified in extracts of exponentially growing synchronous cultures of Chlamydomonas reinhardii, and DNA polymerases A and B were characterized in detail. Both enzymes have the same binding affinity for DEAE-cellulose at pH 7.8, but can be distinguished from each other by their behaviour on phosphocellulose and DNA-agarose. ‘Activated’ calf thymus DNA was used as template, and the pH, K+ and bivalent-cation optima were measured. DNA polymerase A sediments at 5.3 S in glycerol gradients, with an apparent mol.wt. of 90000-100000. Polymerase B sediments between 8S and 10S in 100mM-KCl, the predominant species having an apparent mol.wt. of 200000. In 200mM-KCl, polymerase B dissociates to a single species, which sediments at 5.8S. A 3S species was found in aged preparations of both enzymes. The activity of polymerase B from cells harvested during nuclear DNA synthesis is twice that found in Chlamydomonas at other times during the cell cycle.
TL;DR: It is concluded that the genes for ribosomal RNA are equally reiterated in spores, hatching amoebae and in plasmodia and they appear to be similarly organised in all stages of the life cycle examined so far.