Showing papers on "Nuclear DNA published in 1976"
TL;DR: A relationship between the basic nuclear DNA content and the occurrence and degree of endopolyploidy is reported and strongly suggests that DNA endoreduplication can be regarded as an evolutionary alternative to the high nuclearDNA content that has been achieved in other species mainly by ‘saltatory replications’.
Abstract: DNA endoreduplication and related phenomena (such as endomitosis, polyteny, nuclear restitution and somatic polyploidy in general) are widespread over the animal and plant kingdoms, although they occur most frequently among insects and angiosperms1–3. The systematic restriction to certain phyla and species has been interpreted in terms of high genetic control of such events3, whereas the characteristic developmental pattern of various degrees of endopolyploidy has been considered as an expression of their functional role in differentiation and synthesising capacity of the cells2,4,5. Recently,however, any role of endoreduplication in cell differentiation has been questioned because of the existence of species apparently lacking endopolyploidy6. All previous discussions on endoreduplication, endopolyploidy and polyteny have, however, ignored the basic DNA contents of the species studied. We here report a relationship between the basic nuclear DNA content and the occurrence and degree of endopolyploidy. This strongly suggests that DNA endoreduplication can be regarded as an evolutionary alternative to the high nuclear DNA content that has been achieved in other species mainly by ‘saltatory replications’.
233 citations
TL;DR: This work describes here how radiation damage in DNA and its repair can be detected simply in the white cells of human blood, and applies the method to detect the damage caused by mitomycin C.
Abstract: DIRECTLY or indirectly phosphodiester bonds in DNA are broken when living cells are irradiated by ionising radiations or ultraviolet light. There are various sophisticated techniques for monitoring radiation damage1–6. We describe here how radiation damage in DNA and its repair can be detected simply in the white cells of human blood. The method is very sensitive and should prove useful in screening populations for abnormal repair mechanisms. As there is also great interest in methods for detecting environmental agents that damage DNA2,7, we have applied the method to detect the damage caused by mitomycin C.
185 citations
TL;DR: It is concluded that the highly characteristic general design of bulk nDNA, and of the majority of individual sub-fractions of n DNA, is shared by those fractions of nDNA that code for proteins which in turn implies that they have all evolved in response to the same major selection pressures.
157 citations
TL;DR: Cell size, the nucleocytoplasmic ratio, and the DNA content of the nucleus are mutually interdependent and it is justifiable to use the data on one of these features for the approximate determination of the others.
Abstract: Publisher Summary Cell size, the nucleocytoplasmic ratio, and the DNA content of the nucleus are mutually interdependent. It is, therefore, justifiable to use the data on one of these features for the approximate determination of the other two. In the evolutionary process, every factor that favors a change in one of these characters influences the state of the other two. For vertebrates, the primitive DNA content was probably not very different from the actual state in Latimeria , many elasmobranchs, and some anurans. It is moderately reduced in mammals. In Dipnoi and Urodela , DNA content and cell size are greatly increased. A reduction in both these features occurred in reptiles, birds, and the majority of teleosts. Regularities occur in the cell size of passerine birds, which suggest that they are indispensable for a high metabolism. The diverse levels of cell-size variability in other vertebrates demonstrate that natural selection may be indifferent to changes in cell size unless they are fairly pronounced. Natural selection could have decreased cell size and DNA content when it favored a decrease in overall size of the organism, speed of development, high metabolism, and rejection of unused genetic information. An increase in DNA content and in cell size could be favored as a means of economizing in structural material with an enlargement of the body and a reduction in maintenance costs. It could confer a greater resistance of cells to changes in the composition of body intercellular fluids.
123 citations
TL;DR: The relationships of satellite DNA to karyotype structure reveal a new level of hierarchy in the genome that appears capable of exerting global control over environmental adaptation and the evolution of new species.
Abstract: The genusDipodomys (kangaroo rats) exhibits major interspecies variations in the proportions of highly reiterated satellite DNA sequences in the genome as well as in the chromosome number and the proportions of uni-armed and bi-armed chromosomes. For nearly all of the approximately 22 species of the genus and several subspecies, liver DNA was distributed in neutral CsCl buoyant density gradients into four fractions: principal DNA (1.698 g/ml), intermediate-density DNA (1.702 g/ml), MS satellite (1.707 g/ml) and HS (heavy) satellites (1.713 g/ml). The total nuclear DNA content of diploid liver cells measured in eleven species by quantitative cytophotometry, ranged from 6.9 to 10.9 pg. These data were correlated with known features of the karyotypes of individual species. The salient findings were: (1) that interspecies variations in diploid chromosome number cluster at 52–54, 60–64 and 70–72 (2) that high total nuclear DNA was associated with high chromosome number, and with relatively large amounts of satellite DNA (3) that a high ratio of HS satellites to intermediate-density DNA was generally correlated with a predominance of metacentric and submetacentric chromosomes (high fundamental number). The relationships of satellite DNA to karyotype structure reveal a new level of hierarchy in the genome that appears capable of exerting global control over environmental adaptation and the evolution of new species. This mechanism is consistent with recent hypotheses that changes in the macro-structure of the genome are more important than point mutations in facilitating the rapid phases of animal evolution.
120 citations
TL;DR: Evidence indicates that the quantitative changes in the genus Lathyrus involve mainly the repetitive, as distinct from the non-repetitive fraction of the chromosomal DNA and, on a cytological basis, mainly heterochromatin in contrast to euchromatin.
Abstract: In the genus Lathyrus the divergence and evolution of species was accompanied by large scale changes in nuclear DNA amount. All the species are diploids with 14 chromosomes so that the DNA changes were the result of amplification or deletion of segments within chromosomes. Our evidence indicates that the quantitative changes involve mainly the repetitive, as distinct from the non-repetitive fraction of the chromosomal DNA and, on a cytological basis, mainly heterochromatin in contrast to euchromatin. There is an element of discontinuity in the distribution of DNA amounts among species which suggests that the DNA variation results from a series of separate, spasmodic events. The discontinuities may be viewed, also, as “steady states” from the standpoint of genetic balance and biological fitness.
104 citations
TL;DR: The constancy of the nuclear DNA amounts among provenances of White Spruce and of the other species growing in widely differing environments is both surprising and impressive, and provides further testimony to the pronounced inertia to quantitative DNA change within species.
Abstract: There are numerous reports of a very wide range of variation in nuclear DNA amounts among populations within species of the Pinaceae, including Picea glauca, the White Spruce. Our survey of 26 provenances, covering almost the entire range of White Spruce in North America showed, in contrast, no significant variation in nuclear DNA amount within the species except for minor fluctuations due to B chromosomes. The DNA estimates, throughout, fall within the range of 37·4 to 40·4 × 10−12 g. The areas of the 2C nuclei measured at G1 from 12 provenances were also highly uniform. In addition, there was no significant variation in the chromosome volume between and within provenances. Both facts reinforce the conclusion that nuclear DNA amounts within the species are constant. There are no detectable differences in the nuclear DNA content between Picea glauca and P. engelmannii. In Pinus contorta as in P. glauca, nuclear areas and DNA amounts do not vary significantly between or within provenances and the mean DNA value of 2C nuclei is 40·34 × 10−12 g. White Spruce in North America alone ranges over 3000 miles of longitude and some 1000 miles of latitude. The constancy of the nuclear DNA amounts among provenances of White Spruce and of the other species growing in widely differing environments is both surprising and impressive. It provides further testimony to the pronounced inertia to quantitative DNA change within species.
82 citations
Journal Article•
TL;DR: It is suggested that under the conditions used here the following different processes may have contributed to the total incorporation of BP products into nuclear DNA: (a) formation of DNA-binding products derived from BP by nuclear aryl hydrocarbon hydroxylase; (b) formationOf DNA- binding products from microsomal BP metabolites by nuclear Aries hydrase; and (c) direct transfer of reactivemicrosomal metabolites to nuclear DNA.
Abstract: Summary The hepatic nuclear fraction isolated from 3-methylcholanthrene (MC)-treated rats contained enhanced levels of cytochrome P-450 and aryl hydrocarbon hydroxylase [benzo( a )pyrene (BP) monooxygenase], whereas the activities of epoxide hydrase and reduced nicotinamide adenine dinucleotide phosphate-cytochrome c reductase and the concentration of cytochrome b 5 were not altered. The metabolite pattern of BP was investigated by using high-pressure liquid chromatography and was found to be similar in nuclei and microsomes from MC-treated rats. After incubation of the nuclear fraction with [ 3 H]BP and reduced nicotinamide adenine dinucleotide phosphate, radioactivity was found to be associated with nuclear DNA and the extent of binding was markedly enhanced by pretreatment of the animals with MC. Binding was strongly inhibited by α-naphthoflavone but was not influenced by 1,1,1-trichloropropene-2,3-oxide, an inhibitor of epoxide hydrase. In the presence of microsomes from MC-treated rats, increased binding of BP to DNA was observed in nuclei from both control and MC-treated rats; moreover, when the nuclear DNA was replaced by a corresponding amount of calf thymus DNA, the extent of binding was severalfold enhanced. In contrast to nuclei from control rats, the nuclear fraction from MC-treated rats showed an increase in bound radioactivity when incubated with a microsome-free supernatant, obtained by incubating microsomes from MC-treated rats with [ 3 H]BP. The increase in extent of binding was eliminated in the presence of menadione or α-naphthoflavone. It is suggested that under the conditions used here the following different processes may have contributed to the total incorporation of BP products into nuclear DNA: ( a ) formation of DNA-binding products derived from BP by nuclear aryl hydrocarbon hydroxylase; ( b ) formation of DNA-binding products from microsomal BP metabolites by nuclear aryl hydrocarbon hydroxylase; and ( c ) direct transfer of reactive microsomal metabolites to nuclear DNA.
74 citations
TL;DR: There is wide variation in chromosome size and nuclear DNA amount between the 22 species studied within the genus Crepis, with the most primitive perennial species having higher DNA values than the more advanced annual species.
Abstract: There is wide variation in chromosome size and nuclear DNA amount between the 22 species studied within the genus Crepis. The changes in DNA amount involve all, or most of, the chromosomes within species complements, but structural rearrangements due to inversions and interchanges have made the distribution of changes somewhat unequal. There is an evolutionary reduction in the amount of DNA with the most primitive perennial species having higher DNA values than the more advanced annual species. The advanced species have more chromosomes with median centromeres than the primitive species and show increased symmetry. Nuclear DNA amount is positively correlated with both seed size and pollen grain size.
73 citations
TL;DR: In separate experiments, the incorporation of [3H]thymidine into DNA of peritubular myoid cells was shown to be independent of FSH or dbcAMP, and DNA synthesis was abolished by prior treatment of cells with cytosine arabinoside.
55 citations
TL;DR: The genome of the cellular slime mold Dictyostelium discoideum has been analyzed by limit digestion with Eco R1 restriction endonuclease and analysis by renaturation kinetics indicates that it is repeated approximately 200 times per haploid genome and that it was not internally repeated.
TL;DR: Rat liver nuclei were incubated with microsomes, a NADPH-generating system, microsome and 3H-benzo (a) pyrene to confirm the presence of a nuclear aryl hydrocarbon hydroxylase and extend previous studies on macromolecular acceptors to include nuclear proteins to demonstrate reduced binding to nuclear proteins and DNA.
TL;DR: The dependence of reassociation kinetics on DNA fragment length for the four species indicates for all of them an interspersed organization of the various sequence classes.
Abstract: DNA reassociation kinetics were studied, by means of the hydroxyapatite chromatography method, for four species of Amphibians with different nuclear DNA content: Xenopus laevis (3 pg DNA per haploid genome) and Bufo bufo (7 pg) of the Anura subclass and Trituras cristatus (23 pg) and Necturus maculosus (52 pg) of the Urodela subclass. Within each subclass the two species studied were found to have about the same absolute amount of unique DNA. The differences of total nuclear DNA can be accounted for by quantitative variations of the repetitive sequence classes, at least in part due to changes in the number of copies of the various sequences. On the contrary the great difference in nuclear DNA between the two subclasses, Anura and Urodela, involves all sequence classes in parallel; the slowly reassociating fraction appears to be unique in spite of a tenfold difference in absolute amount. The dependence of reassociation kinetics on DNA fragment length for the four species indicates for all of them an interspersed organization of the various sequence classes.
TL;DR: The hypothesis that the formation of foldback DNA is mainly an intrastrand phenomenon, but nevertheless occurs at different sites in different sets of the Xenopus laevis genome is adopted.
TL;DR: The kinetics indicate that nuclear DNA, with the exception of ribosomal cistrons, renatures as a single component with an informational complexity 25 times that of the Escherichia coli genome.
TL;DR: Transfer RNA's were isolated from Euglena gracilis and species of tRNA hybridizing to ct DNA were partially purified by hybridization-chromatography, appearing to be different.
Abstract: Transfer RNA's were isolated from Euglena gracilis. Chloroplast cistrons for tRNA were quantitated by hybridizing tRNA to ct DNA. Species of tRNA hybridizing to ct DNA were partially purified by hybridization-chromatography. The tRNA's hybridizing to ct DNA and nuclear DNA appear to be different. Total cellular tRNA was hybridized to ct DNA to an equivalent of approximately 25 cistrons. The total cellular tRNA was also separated into 2 fractions by chromatography on dihydroxyboryl substituted amino ethyl cellulose. Fraction I hybridized to both nuclear and ct DNA. Hybridizations to ct DNA indicated approximately 18 cistrons. Fraction II-tRNA hybridized only to ct DNA, saturating at a level of approximately 7 cistrons. The tRNA from isolated chloroplasts hybridized to both chloroplast and nuclear DNA. The level of hybridization to ct DNA indicated approximately 18 cistrons. Fraction II-type tRNA could not be detected in the isolated chloroplasts.
TL;DR: It is suggested that the novel DNA polymerase induced by HCMV infection might be an early protein(s) responsible for viral replication.
TL;DR: This work has shown that fowlpox virus (FPV) stimulates DNA synthesis both in vivo and in vitro, which, together with the ability of FPV to cause hyperplasia in vivo, suggests that the host cell nucleus is affected during FPV infection.
TL;DR: The life history of Coleochaete scutata Bréb was analyzed by Feulgen microspectrophotometry, a technique measuring DNA content in individual nuclei by correlating nuclear DNA content with morphological structures or stages in the life history.
Abstract: SUMMARY
The life history of Coleochaete scutata Breb. was analyzed by Feulgen microspectrophotometry, a technique measuring DNA content in individual nuclei. By correlating nuclear DNA content with morphological structures or stages in the life history, changes in ploidy level are revealed.
The microspectrophotometric study confirmed the earlier reports of a haploid vegetative thallus with mitotic division restricted primarily to the margin of the thallus. In the mitotic cycle the G1 (pre-synthesis) phase is longer in duration than the synthesis find G2 (post-synthesis) phases. Oogamous sexual reproduction results in resistant oospores which attain DNA levels of 2C 8C (1C being the DNA level of gamete nuclei).
TL;DR: An ATP-dependent DNA ligase has been demonstrated in extracts of rat liver mitochondria, demonstrating an intramitochondrial localization and the properties of the partially purified enzyme are similar to those of the nuclearDNA ligase from rat liver.
TL;DR: Nuclear and mitochondrial DNA replication were monitered during the development of synchronous yeast zygotes during the zygotic formation and maturation period to derive the diploid level of both nuclear and mitochondrialDNA.
Abstract: Nuclear and mitochondrial DNA replication were monitered during the development of synchronous yeast zygotes. Purified first zygotic buds were also analyzed. Nuclear DNA replicated discontinuously but coincidently with bud initiation, while mitochondrial DNA replicated throughout the zygotic formation and maturation period. First zygotic buds contained the diploid level of both nuclear and mitochondrial DNA.
TL;DR: This work has shown that the sites of nuclease digestion are regularly spaced, and that, at the limit of digestion, the majority of the DNA that remains is in the form of relatively homogeneous small fragments.
Abstract: RECENT evidence indicates that a large portion of the DNA of higher organisms is organised in compact nucleoprotein structures. Initial studies on nuclease digestion of chroma-tin showed that about half the nuclear DNA is present in the form of small resistant chromatin fragments1–3. Subsequent studies have shown that the sites of nuclease digestion are regularly spaced, and that, at the limit of digestion, the majority of the DNA that remains is in the form of relatively homogeneous small fragments, which vary from about 120 to 200 nucleotide pairs in length4–7. This concept of small repeating resistant structures in chromatin is further supported by electron microscope studies on chromatin fibres spread from hypotonically treated nuclei8 and from isolated chromatin9.
Journal Article•
TL;DR: Human liver cell nuclei obtained from liver biopsies in 18 patients with normal or practically normal liver histology as judged by light microscopy were studied and higher correlations were found between nuclear nucleic acid content and size and between nuclear protein content and nuclear size.
Abstract: Cytophotometry was performed on human liver cell nuclei obtained from liver biopsies in 18 patients with normal or practically normal liver histology as judged by light microscopy. Imprints of liver cells and liver cells or liver cell nuclei obtained by different isolation procedures were studied. The nuclear DNA, total nucleic acid and protein content was evaluated after Feulgen, gallocyanin and naphtol-yellow staining and by UV-spectrophotometry. The nuclear area was obtained during the cytophotometric scanning procedure (Zeiss UMSP I). A total of 2,330 nuclei were investigated and approximately 80 per cent of these were diploid. The diploid value was confirmed by UV-spectrophotometry where a total nucleic acid content of approximately 7 pg was found. The nuclei could be grouped in classes corresponding to di-, tetra- and octaploid nuclei, according to their contents of DNA, total nucleic acid and protein and according to their size. The variation in nuclear contents was lowest for DNA with a coefficient of variation of approximately five percent, and highest for the protein content (15 per cent). Within diploid nuclei, insignificant as well as significant correlations between DNA content and size were found, but taken all together a weak positive correlation is likely. Higher correlations were found between nuclear nucleic acid content and size and between nuclear protein content and nuclear size.
TL;DR: The results suggest that with divalent cations present, the histone basic charges are more uniformly distributed along whole nuclear DNA.
Abstract: Thermal denaturation of deoxyribonucleic acid (DNA) in situ in individual unbroken cells is studied by a cytofluorometric method. This method allows us to investigate DNA denaturation in the presence of divalent cations at concentrations reported to be necessary to maintain native structure of nuclear chromatin. Under these conditions the pattern of DNA denaturation is very different than when studied in the presence of ethylenediaminetetraacetate or citrate. The results suggest that with divalent cations present, the histone basic charges are more uniformly distributed along whole nuclear DNA. Various cell types exhibit great differences in sensitivity to DNA denaturation when assayed in the presence of 1 mM MgCl2. Human lymphocytes, monocytes and certain kinds of human leukemic cells show differences large enough to be used as a parameter for their recognition in mixed samples. Possible applications of the method in basic research on chromatin conformation and as a tool for cell recognition in diagnosti...
TL;DR: Both nuclear structure and DNA content indicate DNA (heterochromatin) underreplication to occur in certain cells of the suspensor in early embryogenesis.
Journal Article•
TL;DR: Just as after 70% hepatectomy, the activity of the 7.1 S DNA polymerase is elevated in liver nuclei from unoperated animals in which hepatic DNA replication has been induced with a mixture of biochemicals or by a dietary manipulation, the stimulated intact livers show a relationship between the increases in the enzyme activity and thymidine incorporation in vivo.
Abstract: Just as after 70% hepatectomy, the activity of the 71 S DNA polymerase, but not the 32 S polymerase, is elevated in liver nuclei from unoperated animals in which hepatic DNA replication has been induced with a mixture of biochemicals or by a dietary manipulation Again as with regenerating liver, the stimulated intact livers show a relationship between the increases in the enzyme activity and thymidine incorporation in vivo over a wide range of hepatic responses These observations are consistent with a role for the 71 S activity in nuclear DNA replication Cytosine arabinoside 5'-triphosphate and novobiocin can be used to distinguish between the 32 S and 71 S polymerases from nuclei of stimulated intact liver as well as of regenerating liver
TL;DR: Using sea urchin anucleate fragments, it was able to demonstrate that all eight messenger RNAs are transcribes from mitochondrial DNA, rather than being transcribed from nuclear DNA and imported into the mitochondria.
TL;DR: Data suggest that while chromosome fragmentation could have generated the present-day range of chromosome numbers in the genus, there have also been changes in the total quantity of DNA with the result that species with similar chromosome numbers have different DNA contents.
Abstract: The dimensions of metaphase chromosomes and nuclear DNA contents were measured in eight species ofLuzula. The 2 C DNA contents ranged from 8.51 pg inL. purpurea to 0.55 pg inL. pilosa. Total chromosome volume shows a linear relationship with DNA content; however, the total chromosome length of the complement of the different species is approximately constant. Nucleolar volume and the number of chromocentres in the different species also show a relationship with DNA content. Taken together, these data suggest that while chromosome fragmentation could have generated the present-day range of chromosome numbers in the genus, there have also been changes in the total quantity of DNA with the result that species with similar chromosome numbers have different DNA contents. The relationships of DNA content with chromosome volume inLuzula and other genera are compared and the differences discussed.
TL;DR: Although total dry mass and non-nucleolar nuclear dry mass showed significant regression on DNA content, the nucleolar dry mass gave a much wider scatter, indicating that nucleolar mass is not equally dependent on nuclear DNA content.
Abstract: Estimations on nuclear DNA content, nuclear area and nuclear dry mass were made on 13 species of Crotalaria, with the help of Vicker's M 85 microdensitometer and Vicker's interferometer. Highly significant differences for all three characters were found between species. DNA density (DNA/area) increased with increase in DNA content. The cultivated species, C. juncea had a lower DNA density relative to its DNA content.—Nuclear DNA made only a small fraction of nuclear dry mass (1∶15). Although total dry mass and non-nucleolar nuclear dry mass showed significant regression on DNA content, the nucleolar dry mass gave a much wider scatter, indicating that nucleolar mass is not equally dependent on nuclear DNA content.
TL;DR: It may be expected that DNA-RNA hybridization and Giemsa staining procedures will reveal differences in karyotypes between species in genera where genomes at present exhibit only moderate differences between species.
Abstract: Although relatively few biochemical studies have been carried out on woody plants, interesting correlations (and discrepancies) have been noted between nuclear DNA content and several parameters such as geographic range (latitude), ecological adaptation, nuclear volume, and karyotypic differences such as chromosome length. Hybridization between genomes with complements possessing chromosomes of different relative sizes, B chromosomes, and repetitious DNA and heterochromatin, have been reasons advanced for changes in karyotypes and nuclear DNA response. B chromosomes may not be as rare in tree species as previously considered. It may be expected that DNA-RNA hybridization and Giemsa staining procedures will reveal differences in karyotypes between species in genera where genomes at present exhibit only moderate differences between species. While successful callus production has been induced for a number of woody species, so far no haploid trees have been produced. In Betula there appears to be little barrier to cross fertilization and plants with different euploid chromosome numbers have been obtained from seed from the same parental tree.